The navigation device retrieving a route and performing route guidance along the route is in widespread use. Such a navigation device searches for a route with minimum cost from a present position being a starting point to a destination being an end point.
Cost is various. The cost includes not only a travel distance and a travel time but also a task process such as a right turn and a left turn, which increase a driving workload. That is, a technology for selecting an optimum route includes a view concerning how to reduce driver's workload.
In view of this, there is proposed a navigation device that sets a route to the same route once traveled before (see Patent Literature 1 for example). This device stores a locus data to a destination and sets a return route from the destination based on the locus data.